Pearson International A Level Physics Core Practical 3: Determine the Young modulus of a material

This core practical is part of Pearson's practical-learning programme. The method below is one defensible implementation, not a confidential instruction sheet. Centres may adapt equipment while preserving the scientific purpose, controls, measurements and safety requirements.

Aim and scientific principle

Measure extension under load and combine the force-extension gradient with specimen length and area to determine Young modulus.

Begin by translating the title into a testable question. Identify what is deliberately changed, what is measured directly, what is calculated and what must remain controlled. Predict a relationship only after naming the mechanism. A prediction without a reason is weak; a reason without measurable variables cannot guide a practical design.

Apparatus and setup

Use long wire, fixed support, pulley and masses or force sensor, fiducial marker, ruler, micrometer and safety screen. Select every measuring instrument by range and resolution, not by name alone. Draw a labelled scientific setup that shows the working geometry and exactly where readings are taken. Include a control or blank when it distinguishes the target effect from drift, contamination or background response.

Before collecting results, check zero readings, calibration, leaks, alignment or sterility as relevant. Record the instrument resolution beside the first raw-data table. If a digital device displays more digits than its underlying accuracy supports, do not treat every digit as equally certain.

Method

1. Measure original wire length and diameter at several positions and directions.
2. Apply a small preload, define zero and add loads in safe increments.
3. Record extension after settling, unload to check elastic return and repeat readings.
4. Plot force against extension and use the linear-region gradient with geometry to calculate modulus.

Plan the analysis before starting. This reveals whether an additional measurement is needed for a derived quantity and prevents a completed experiment from lacking a mass, length, concentration, background or calibration value. A method should be detailed enough for another trained student to reproduce, while avoiding decorative steps that do not affect validity.

Variables and controls

• Independent variable: applied force within the elastic region.
• Dependent variable: extension.
• Important controls: wire material and length, temperature, loading rate, diameter measurement and zero reference.